Observation planning algorithm of a Japanese spaceborne sensor: Hyperspectral Imager Suite (HISUI)

Hyperspectral Imager Suite (HISUI) is a Japanese future spaceborne hyperspectral sensor system. It will be launched in 2015 or later as one of mission instruments onboard JAXA's Advanced Land Observation Satellite 3 (ALOS-3). HISUI will consist of a hyperspectral imager and a multispectral imager with 30 m and 5 m spatial resolution and 30 km and 90 km swath, respectively. In order to characterize capability to detect seaweed beds of HISUI multispectral data with 5 m spatial resoution, we comprared classification results between ALOS/AVNIR-2 with spatial resolution of 10 m and simulation data of HISUI produced from WorldView-2. Study site was seletced in Oita Prefecture in Kyushu Island, Japan, where seaweed beds were broadly distributed along the coast. We used AVNIR-2 data taken on 20 February 2007 and simulation data produced from WorldView-2 taken on 18 April 2010. Supervised and unsupervised classifications were applied to these data sets. Miss-classification of analysis using AVNIR-2 was identified in deep waters in offshore waters. Since radiometric resolution of AVNIR-2 is 8 bits, it is considered that low radiometric resolution causes missclassification. Spatial resolution of HISUI multiband data with 5 m permits to detect seaweed beds clearer. Precision of classification using HISUI simulation data was about 90% and 10% higher than that using AVNIR-2. Thus HISUI multiband data are suitable for mapping seaweed beds in coastal waters.

Hyperspectral Imager Suite (HISUI) is a future spaceborne hyperspectral Earth imaging system being developed by Japanese Ministry of Economy, Trade, and Industry (METI). HISUI will be launched and deployed on International Space Station (ISS) for two - three year operation from 2020. Manufacturing and testing of HISUI Flight Model were almost completed, and design of HISUI Exposed Payload System is being conducted. HISUI data policy and research announcement as well as synergy with other earth observing instruments onboard ISS are also being discussed.

The International Space Station has become the platform for deploying hyperspectral sensors covering the solar reflective spectral range for earth observation. Intercalibration of hyperspectral sensors plays a crucial role in evaluating/improving radiometric consistency. When intercalibrating between hyperspectral sensors, spectral band adjustment is required to mitigate the effects of differences between the relative spectral responses (RSRs) of the sensors. Errors in spectral parameters used in spectral band adjustment are propagated through to the adjustment results. The present study analytically approximated the uncertainty in the spectral band adjustment for evaluating the relative contributions of uncertainties in parameters associated with the exo-atmosphere, atmosphere, and surface to the total uncertainty. Numerical simulations using the derived equations were conducted to perform a sensitivity analysis for the case of the spectral band adjustment between the Climate Absolute Radiance and Refractivity Observatory (CLARREO) Pathfinder (CPF) and the Hyperspectral Imager Suite (HISUI). The results show that the effects of errors in the solar irradiance were greater than those of other sources of error, indicating that accurate estimates of atmospheric reflectances and tranismittances are not needed for spectral band adjustment between CPF and HISUI in the atmospheric windows. The accuracy of the analytical approximation was also evaluated in the simulations. The framework of the sensitivity analysis is applicable to other pairs of hyperspectral sensors.

This paper reports on the initial analysis of spectral smile calibration of the Hyperspectral Imager Suite (HISUI) onboard the International Space Station, which has been continuously acquiring data since September 4, 2020. HISUI is an optical hyperspectral imager consisting of two subsystems: VNIR covering 400 to 980nm at intervals of 10 nm, and SWIR covering 895 to 2481nm at 12.5nm intervals. Based on the atmospheric correction for actual observation images, we assessed cross-track dependences of the wavelength deviation (spectral smile) and the full-width at half-maximum (FWHM) of the HISUI response function. We found that significant spectral smile was observed, with maximum variations of 1.8nm in VNIR and 4.3–4.5nm in SWIR. In addition, the cross-track variation of FWHM was observed with maximum variations of 5.0nm for VNIR and 2.5–3.5nm for SWIR.We used the results to model the smile functions to update a smile correction table in the internal calibration system of HISUI. Then, we evaluated how the smile functions reduce the spectral smile in the data acquired after the update on September 27, 2021.We confirmed that VNIR showed a nearly flat profile within 0.25nm with a nearly constant FWHM. For SWIR, although a slight amount of spectral smile and a variation of FWHM were still observed partly due to wavelength dependence in the spectral smile, the spectral smile was reduced to <~2.2 nm. This study demonstrated that wavelength calibration using actual observation images for ground surfaces is important for the characterization of hyperspectral sensors.

Fast and small-footprint lossless compressors for multi and hyper-spectral sensors have been developed. The compressors are employed for HISUI (Hyper-spectral Imager SUIte: the next Japanese earth observation project that will be on board ALOS-3). By using spectral correlations, the compressor achieved the throughput of 30Mpel/sec for hyper-spectral images and 34Mpel/sec for multi-spectral images, which covers the data acquisition throughput of HISUI, on a radiation tolerant FPGA (field-programmable-gated-array). We also implemented the compressor on the evaluation model device of HISUI, and confirmed its feasibility and compression performance of actual hyper-spectral sensor data.

Japan Space Systems has conducted the application studies for HISUI, the Hyper-spectral Imager SUIte, since FY 2007. Our studies cover various fields such as oil, gas and mineral resources, agriculture and environment. This report summarizes some of the outcomes, including alteration mineral mapping, paddy growth estimation, coral reef monitoring and forest type classification, and introduces the anticipated benefits of HISUI imagery for future data users.

Hyperspectral Imager Suite (HISUI) was launched in December 2019 and successfully attached to Japan Experiment Module Exposed Facility, International Space Station. Due to data communication problems, its initial check out activities have been delayed, but its first light image was acquired and released in September 2020. HISUI data delivery to Research Users will start in 1Q of Japanese FY2021 (April - June 2021).

Municipal solid waste management remains a major environmental challenge across Africa, where rapid urbanisation has outpaced formal waste infrastructure and routine landfill monitoring is often absent. Rather than proposing a classification algorithm, this study investigates whether spaceborne hyperspectral imagery can reveal robust spectral fingerprints of landfill surfaces suitable for automated detection. Eight landfill sites across seven African countries were analysed using Hyperspectral Imager Suite (HISUI) data (400–2500 nm, 20 m resolution). A segment-based framework was applied after masking low signal-to-noise regions, combining brightness analysis, L2-normalised spectral shape comparison using Spectral Contrast Angle (SCA), and derivative spectroscopy across 109,275 pixels from six land-cover classes. Brightness-based discrimination exhibited strong inter-site variability, limiting its general applicability. In contrast, shape-based metrices revealed consistent separability between landfill-active surfaces and soil or urban classes in the shortwave infrared (SWIR), particularly within the 1538–1750 nm and 2075–2474 nm regions. Derivative analysis further identified stable extrema near approximately 1700 nm and 2200–2300 nm across all sites, indicating reproducible curvature-based fingerprints associated with exposed municipal solid waste. These results demonstrate that landfill surfaces exhibit intrinsic SWIR spectral characteristics that persist across diverse African environments. This study establishes the first multi-site hyperspectral library of African landfill surfaces, providing a physical basis for developing generalised landfill detection frameworks.

Hyperspectral Imager Suite (HISUI) is a Japanese hyperspectral mission to obtain optical images ranging from visible to shortwave infrared region. The mission instrument will be on-board the Japanese Experiment Module (JEM) of the International Space Station (ISS) in early 2020. The sensor obtains spectral images of 185 bands with the ground sampling distance of 20x31 meter, which succeeds the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) in the visible and shortwave infrared region. After the critical design review in 2014, integration of the Flight Model (FM) of HISUI sensor was completed in the beginning of 2017. In parallel, the bus system connecting HISUI sensor and the JEM External Facility (EF) is developed, which has the function of a data recorder, electric control, navigation, thermal control and mechanical structure is under development. Since hyperspectral data needs an accurate calibration, the ground-based test is under way. In this work, the present status of HISUI sensor is presented. Sensor performances in terms of optical distortion and radiometric performances are described based on the FM tests.

As mentioned above, the simulation program is useful to investigate observation-planning strategy and rules for improving efficiency of observations.

Vena cava filter (VCF) application is the method of choice to prevent recurrent pulmonary embolism in patients with deep venous thrombosis. Because of the reported complications after VCF placement we summarize our long-term follow-up results with the LGM and Titanium Greenfield (TG) devices. Eighty-seven LGM VCF and 17 TG VCF were placed in 104 patients (average age 64 years). The follow-up examinations were performed by color-coded duplex sonography, plain radiographs, cavography, and computed tomography (CT). The maximum observation time was 81 months. Filter migration occurred in 11% (8/76) of the LGM VCF and 15% (2/13) of the TG VCF. Vena cava thrombosis was seen in 17% (13/76) of the patients with an LGM VCF and in 31% (4/13) of those with a TG VCF. The patency rate was 95% (72/76) for the LGM VCF and 92% (12/13) for the TG VCF. Pulmonary embolism was noted in 3 patients after LGM VCF insertion and in no patient after TG VCF insertion. A VCF should only be inserted in a patient after pulmonary embolism and when there is strict proof of the indication.

Optimal small satellite orbit design based on robust multi-objective optimization method

ZY-1 02D is China’s first civil hyperspectral (HS) operational satellite, developed independently and successfully launched in 2019. It can collect HS data with a spatial resolution of 30 m, 166 spectral bands, a spectral range of 400~2500 nm, and a swath width of 60 km. Its competitive advantages over other on-orbit or planned satellites are its high spectral resolution and large swath width. Unfortunately, the relatively low spatial resolution may limit its applications. As a result, fusing ZY-1 02D HS data with high-spatial-resolution multispectral (MS) data is required to improve spatial resolution while maintaining spectral fidelity. This paper conducted a comprehensive evaluation study on the fusion of ZY-1 02D HS data with ZY-1 02D MS data (10-m spatial resolution), based on visual interpretation and quantitative metrics. Datasets from Hebei, China, were used in this experiment, and the performances of six common data fusion methods, namely Gram-Schmidt (GS), High Pass Filter (HPF), Nearest-Neighbor Diffusion (NND), Modified Intensity-Hue-Saturation (IHS), Wavelet Transform (Wavelet), and Color Normalized Sharping (Brovey), were compared. The experimental results show that: (1) HPF and GS methods are better suited for the fusion of ZY-1 02D HS Data and MS Data, (2) IHS and Brovey methods can well improve the spatial resolution of ZY-1 02D HS data but introduce spectral distortion, and (3) Wavelet and NND results have high spectral fidelity but poor spatial detail representation. The findings of this study could serve as a good reference for the practical application of ZY-1 02D HS data fusion.

Computers are being used extensively in the manufacturing industry to design and analyze products. In spite of the power of existing CAD systems and potential power of current Design Automation systems, we believe that they possess an inherent limitation that keeps them from aligning with and fully supporting the design process. Specifically, all of these systems are based on using parametric operators to generate valid designs. This paper examines the limitations of parametric operators for CAD and design automation and shows how “variational” methods could be used. An approach using variational methods is compared with traditional CAD and design automation methods. The paper also proposes a language of objects and relationships to represent design requirements. This work is a step towards realizing an interactive design synthesis system that can represent and satisfy design requirements.

The key performance criteria listed in ANSI S12.60-2002, Acoustical Performance Criteria, Design Requirements and Guidelines for Schools, are that the maximum background noise is limited 35 dBA, and that the maximum reverberation time is limited to 0.6 seconds in the most common classroom size. Limits on sound transmission properties of the room envelope are also made. If these performance criteria are met, each student, no matter where he or she sits in the classroom, will be in an environment that affords adequate speech intelligibility, i.e., an adequate opportunity to understand the teacher’s words correctly. During the standard development process, the author had the opportunity to work with his colleges at The Ohio State University. The OSU group made measures in 34 classrooms in the Columbus area (inter-city, suburbs, and rural; public and private). The author analyzed these data, and compared the results with ANSI S12.60-2002 performance criteria. It was found that the background noise levels were around 50 dBA. This is 15 dBA above the standard requirement. A majority of the reverberation times were in line with the 0.6-second criteria, but a significant number had reverberation times around 1 second.